1. Field of the Invention
The present invention relates to a chemical vapor deposition raw material comprising an organoplatinum compound for producing a platinum thin film or a platinum compound thin film by a chemical vapor deposition method, the CVD method or the ALD method. The present invention particularly relates to a chemical vapor deposition raw material that can form a platinum thin film even at a low temperature of 300° C. or lower while having moderate stability.
2. Description of the Related Art
As an electrode material for a field effect transistor (FET) incorporated into an integrated circuit, a steric Ni—Pt silicide electrode having a three-dimensional structure is known. In the production of this Ni—Pt silicide electrode, it is required that when a Pt thin film and a Ni thin film are formed on preliminarily produced Si having a steric structure, the Si is uniformly covered with the Pt thin film and Ni thin film electrodes in the same proportion along the steric shape. It is assumed that in order to produce such a platinum thin film, the use of a chemical vapor deposition method, such as the CVD method, which provides excellent step coverage, is essential. Also for the gate electrode of an FET, a chemical vapor deposition method, such as the CVD method, which enables film formation at low temperature, is preferred in size reduction and performance enhancement.
As raw materials for producing platinum thin films or platinum compound thin films by the CVD method, many compounds have been conventionally known. Examples thereof include a bis(acetylacetonato)platinum(II) complex (Patent Literature 1), a cyclopentadienyltrimethylplatinum(IV) complex (Patent Literature 2), and a tetrakis(trifluorophosphine)platinum compound (Patent Literature 3). Generally, examples of the required performance of these CVD raw materials include high vapor pressure, and capability of film formation at low temperature due to low decomposition temperature. In addition, in view of handling properties, they are preferably in a liquid state at ordinary temperature.
At such requirements, in order to provide a CVD raw material having higher vapor pressure, a compound in which cyclooctadienyl in which at least one hydrogen atom is replaced by an alkyl group, and alkyl anions having 2 to 4 carbon atoms are coordinated to a platinum atom is provided (Patent Literature 4). As described in Patent Literature 4, when an alkyl group is introduced into cyclooctadienyl that is a ligand, the vapor pressure of the platinum complex decreases due to an increase in molecular weight, thereby providing properties not preferred as a CVD raw material compound. But, in Patent Literature 4, it is described that by the introduction of an alkyl group into cyclooctadienyl, the thermal stability of the platinum complex is improved, and decomposition at the stage of heating and vaporizing the compound can be suppressed.
